1. Field of the Invention
The present application relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a method of driving the liquid crystal display device where a time uniformity of a moving picture response time is improved by reducing an optimization time period for reaching a critical temperature.
2. Discussion of the Related Art
Liquid crystal display (LCD) devices having thin profiles, light weight, and low power consumption have been used in notebook computers, office automation devices, audio/video devices, and the like. Among the various types of LCD devices, active matrix LCD (AM-LCD) devices that employ switching elements and pixel electrodes arranged in a matrix structure are the subject of significant research and development because of their high resolution and superior suitability for displaying moving images. Thin film transistor LCD (TFT-LCD) devices use thin film transistors (TFTs) as the switching elements.
FIG. 1 is a view showing a liquid crystal display device according to the related art. In FIG. 1, a liquid crystal display (LCD) device 10 includes a liquid crystal panel 20 displaying images, a backlight unit 30 supplying light to the liquid crystal panel 20, a control unit 40 supplying a control signal, a gate signal and a data signal to the liquid crystal panel 20, an inverter unit 50 adjusting power supplied to the backlight unit 30 and a system unit 60 controlling the control unit 40 and the inverter unit 50. The liquid crystal panel 20 includes a plurality of pixels to display images by using the gate signal and the data signal, and the backlight unit 30 includes an illuminating means to supply the light to the liquid crystal panel 20. The control unit 40 includes a timing controller formed on a printed circuit board (PCB). The control unit 40 generates and supplies a plurality of control signals and an RGB signal to the liquid crystal panel 20. The inverter unit 50 controls illumination of the backlight unit 30 and receives a dimming signal for adjusting illumination of the backlight unit 30 from the control unit 40 or the system unit 60. In addition, the system unit 60 includes an external interface circuit, such as a television system or a graphic card, to supply an image signal and a plurality of driving signals to the control unit 40 and supply the dimming signal to the inverter unit 50.
An LCD device displays images by re-aligning liquid crystal molecules of a liquid crystal layer. A time for re-aligning the liquid crystal molecules by an electric field may be defined as a response time of the LCD device. As the response time decreases, the liquid crystal molecules are re-aligned more rapidly and a property of the LCD device is improved. Recently, a moving picture response time (MPRT) defined as a response time recognized by human's eyes has been widely used as a standard for estimating a display capability of the LCD device. For example, when the LCD device has a relatively short MPRT, deterioration in display of the LCD device such as a motion blur may be improved.
The MPRT of the LCD device depends on a temperature. For example, as the temperature increases, the MPRT of the LCD device decreases. In addition, the MPRT of the LCD device is saturated over a critical temperature. For example, the critical temperature may be within a range of about 40° C. to about 60° C. Accordingly, the MPRT is optimized over the critical temperature.
Because a turned-off LCD device has a temperature lower than the critical temperature, an optimization time period is required for driving the LCD device with an optimized MPRT over the critical temperature after the LCD device is turned on. FIG. 2 is a graph showing a relation between a moving picture response time and a temperature in a liquid crystal display device according to the related art. In FIG. 2, a turned-off LCD device has a room temperature (RT) of about 20° C. and a first MPRT of MPRT 1. After the LCD device is turned on, as the LCD device is heated up by the backlight unit or the control unit, the temperature of the LCD device increases and the MPRT of the LCD device decreases. In addition, when the LCD device reaches the critical temperature Tc, the MPRT of the LCD device is saturated to a second MPRT of MPRT2. As a result, the LCD device displays images with a uniform MPRT.
Accordingly, during the optimization time period from the room temperature to the critical temperature Tc, the LCD device displays images with an unstable and relatively high MPRT and a display quality of the LCD device is deteriorated. Specifically, the moving image is not properly displayed by the LCD device during the optimization time period. For example, the optimization time period may be over about 1 hour, and the LCD device may display images of unsatisfactory display quality for a relatively long time.